Inter cooler delete good idea or no

[mwiener2]

MAF readings are only valid if everyone is using the same intake and tuned in the same style

[turbodog]

MAF readings are only valid if everyone is using the same intake and tuned in the same style

 

You don't say. Lol. I'm making the reasonable assumption that the perrin test did not change the intake.

[mwiener2]

My point is a MAF reading is usually not a good power indicator

[turbodog]

My point is a MAF reading is usually not a good power indicator

 

Really? If you don't have the air, how are you going to do anything?

 

On any motor there's a pretty limited window for AFR and timing curve between good power and det, for a given ambient temp and fuel grade. Increased airflow, through increased boost pressure or decreased charge temp, is pretty much the only way to make more power.

[sumfoo1]

well.. they only work if they're calibrated correctly too.

 

I mean i'm about to go to a 74mm maf tube so... the calibration could be +/- 10 % and then every other little thing changes it some afta-maf/ turbo inlet etc.

[BAC5.2]

MAF sensors are not calibrated on-car. They are built to spec and calibrated at DENSO. The ECU has no ability to calibrate any sensor. It can compensate sensors, but that is not the same thing.

 

MAF's are a terrible indicator of power, but a great indicator of flow. The two are related, yes, but don't think that means a MAF is a direct indicator. It isn't.

 

A MAF only helps calculate air flow into an engine, but as VE changes dynamically, so does the relationship between MAF voltage and power.

 

Just comparing MAF voltages between two samples, especially when the samples are not utilizing the same physical setup, would tell you very little in terms of useful information.

[sumfoo1]

Lol you're such a dick. Semantics really.

 

I consider translating a maf voltage into an airflow as calibrating it.

The ecu does this. Since our mafs aren't in a self contains housing like mustangs etc. the raw voltage means shit on its own until its scaled and mapped to a verified table. And even that doesn't really mean crap until verified by an 02 sensor.

 

But he is right there are so many things that affect hp at a given airflow. Running at 12 afr if not detonating will make tons more power then running at 10.1. Cam timing, pumping efficiencies etc all can effect the airflow/hp ratio.

 

Btw VE is the measurement of air into the engine vs the displacement of the engine. VE can be measured with a maf so it changing means nothing in this arguement because the maf reading should change with it.

[BAC5.2]

It's not semantics. It's fact. The ECU doesn't calibrate anything. Raw MAF voltage is manipulated by the ECU, but that manipulation factor is based on the calibration of the sensor itself. If there were no cal specs on the sensor, the voltage output would mean nothing in reference to a table.

 

And no, MAF alone will not allow you to calculate VE. VE is impacted by temperature, and since the IAT is built into the MAF, it isn't possible to accurately calculate VE. Temp changes dynamically across the compressor in non-ideal settings (unlike flow across an ideal compressor where temperature is a linear function of pressure. An automotive turbocharger is non-ideal because there is external convective and conductive heating from the turbine and ambient bay temps which fluctuate with vehicle speed, load, and rpm).

 

Air temp at the MAF is not indicative of air temp going into the engine. Therefore, dynamically changing VE is one of the main reasons why MAF readings cannot directly indicate power output. There is no linear relationship between MAF voltage (which indicates only mass flow rate, not volumetric flow rate) and VE.

[sumfoo1]

well then what do you call mapping the maf voltage against actual airflows?

 

All i'm saying is most of us with aftermarket tunes have completely different maf setups thus comparing between two sensors is worthless because some are physically mounted different and others have a completely different scaling. Then that compounded with the fuel burn efficiencies, pumping losses, any knocking etc. makes the MAF give you a +/- 20% estimate of what you could get in hp... which is pretty much worthless.

 

I agree with paragraph 2 but would say if you're going to count that heat gain then you' might as well go to the next step and say you'll never get an actual VE because even the engine heat will effect it through any length of tubing to a certain extent.

 

And i never said volumetric either but i do know it can be calculated to volume with temp and pressure.

 

hell if you want to go that far oxygen density matters too. in the city where there is more CO2 and N2 in the air there is also less 02 which would affect your hp guestimate.

 

All i was saying above is that i agree with you but the bigger variables aren't the one's you're arguing. I can show you a much larger swing based off AFR, octane, ignition timing and cam timing for a given boost level/ parts set then you can with the heat gained during compression not due to compression.

 

And the reason it calculates mass air flow is that the mass shouldn't change regardless but i agree an IAT sensor actually in the intake would be friggin nice.

[BAC5.2]

well then what do you call mapping the maf voltage against actual airflows?

 

Um, mapping maf voltage against a table?

 

You understand that the ECU has NO way of calculating actual airflows, right? It references voltage from the sensor to a table of known values. That table is constructed from the calibration data for the sensor.

 

The ECU does not calibrate the sensor.

 

All i'm saying is most of us with aftermarket tunes have completely different maf setups thus comparing between two sensors is worthless because some are physically mounted different and others have a completely different scaling. Then that compounded with the fuel burn efficiencies, pumping losses, any knocking etc. makes the MAF give you a +/- 20% estimate of what you could get in hp... which is pretty much worthless.

 

Comparing MAF voltages between cars is pointless, I agree. And MAF is not a suitable method for comparing power between two vehicles (or even the same vehicle with hardware changes). To think otherwise shows a lack of understanding.

 

I agree with paragraph 2 but would say if you're going to count that heat gain then you' might as well go to the next step and say you'll never get an actual VE because even the engine heat will effect it through any length of tubing to a certain extent.

 

You COULD go that far, and the point only exacerbates. The fact is that in order to calculate VE using a MAF you HAVE to account for actual combustion temperature. MAF voltage is only one variable in the VE equation, and thus is not going to "change with" VE changes. They are not linear, nor directly related. If you TRIED to map VE calculated through MAF alone, versus actual VE, you'd find extreme deviation.

 

 

And i never said volumetric either but i do know it can be calculated to volume with temp and pressure.

 

You said that VE can be calculated from MAF voltage, and that VE changes would be directly mirrored in MAF voltage changes. That is simply not correct.

 

hell if you want to go that far oxygen density matters too. in the city where there is more CO2 and N2 in the air there is also less 02 which would affect your hp guestimate.

 

That's absolutely correct, which is why calculation of HP from MAF voltage is fundamentally flawed. To think otherwise is simply a showing of lack of understanding.

 

All i was saying above is that i agree with you but the bigger variables aren't the one's you're arguing. I can show you a much larger swing based off AFR, octane, ignition timing and cam timing for a given boost level/ parts set then you can with the heat gained during compression not due to compression.

 

I think you are missing what I'm saying. Fundamentally, VE changes dynamically with respect to MAF voltage. Everything you just mentioned (AFR, fuel content, ignition/cam timing etc) all play into VE. It's the GLOBAL intake over the static displacement of the engine.

[mwiener2]

I don't know what the two of your are arguing over, but I think both of you backedup my claim that a MAF reading is not a good indicator of power.

[BAC5.2]

I don't know what the two of your are arguing over, but I think both of you backedup my claim that a MAF reading is not a good indicator of power.

 

Correct. MAF voltages are completely misleading indicators of power. I was merely explaining why that was the case.

[MDKSDMF]

why not run a nitrous bar on your intercooler if you really need to spray something? dont delete the intercooler, you cant rally with your subaru if u were to run meth only. u would defeat the purpose of the car in general..theres only soo much meth

[meier motor sports]

i wounder if a co2 sprayer on the intercooler would need tuning? wouldnt it lean out the combustionbuy making the charge more dense then the car expects? more air then fuel = lean. or do they not help that much? iv thought about it

[turbodog]

i wounder if a co2 sprayer on the intercooler would need tuning? wouldnt it lean out the combustionbuy making the charge more dense then the car expects? more air then fuel = lean. or do they not help that much? iv thought about it

 

Mass Air Flow.....think about it.

[turbodog]

Um, mapping maf voltage against a table?

 

You understand that the ECU has NO way of calculating actual airflows, right? It references voltage from the sensor to a table of known values. That table is constructed from the calibration data for the sensor.

 

The ECU does not calibrate the sensor.

 

Comparing MAF voltages between cars is pointless, I agree. And MAF is not a suitable method for comparing power between two vehicles (or even the same vehicle with hardware changes). To think otherwise shows a lack of understanding.

 

You COULD go that far, and the point only exacerbates. The fact is that in order to calculate VE using a MAF you HAVE to account for actual combustion temperature. MAF voltage is only one variable in the VE equation, and thus is not going to "change with" VE changes. They are not linear, nor directly related. If you TRIED to map VE calculated through MAF alone, versus actual VE, you'd find extreme deviation.

 

You said that VE can be calculated from MAF voltage, and that VE changes would be directly mirrored in MAF voltage changes. That is simply not correct.

 

That's absolutely correct, which is why calculation of HP from MAF voltage is fundamentally flawed. To think otherwise is simply a showing of lack of understanding.

 

I think you are missing what I'm saying. Fundamentally, VE changes dynamically with respect to MAF voltage. Everything you just mentioned (AFR, fuel content, ignition/cam timing etc) all play into VE. It's the GLOBAL intake over the static displacement of the engine.

 

I think you've needlessly derailed this thread.

 

Mass Air Flow is a measurement of the air mass per unit time flowing into the motor. It is THE primary measured parameter in indicating how much power a motor can make. If other factors are kept the same (AFR, timing, charge temp), there will be a positive correlation, and generally accepted as approximately linear, 1 lb/min = 10 hp. Not accounting for VE, real flow, choke points, etc.

 

Good discussion of MAF's, fueling, and power:

 

http://forums.nasioc.com/forums/showpost.php?p=10538863&postcount=126

 

http://forums.nasioc.com/forums/showpost.php?p=10586635&postcount=7

[NWSPECB]

[mwiener2]

What you're not getting is that I can make a car say it's flowing 20 lb/min at idle. It's just a number.

[BAC5.2]

I think you've needlessly derailed this thread.

 

Not derailment, simply correcting your misinformation.

 

Mass Air Flow is a measurement of the air mass per unit time flowing into the motor. It is THE primary measured parameter in indicating how much power a motor can make. If other factors are kept the same (AFR, timing, charge temp), there will be a positive correlation, and generally accepted as approximately linear, 1 lb/min = 10 hp. Not accounting for VE, real flow, choke points, etc.

"If other factors are the same". But they aren't. ESPECIALLY when changes are made from one vehicle or mod to the next. You said it yourself. "Not accounting for VE...". VE changes dynamically, and non-linearly with MAF voltage.

 

If MAF voltage was the primary measured parameter in indicating how much power a motor can make, then people would simply plot MAF voltage vs. RPM and not waste money putting the car on some silly dyno. But they don't, because it would be worthless. ESPECIALLY when modifications come into play.

 

You DO understand that the MAF sensor simply reports a voltage, right? The flow-table is built from calibrated data. The BEST you can do, is look up mass air flow past the sensor. That is NOT the same as the mass air flow in the engine.

 

Neither of the links you posted are relevant. They simply talk about the relationship between MAF through the sensor tube and sensor voltage. That was never in question.

 

I DO like you you say that 10hp for every lb/min is "generally accepted," when the first link has one person saying that it's a VERY ROUGH guide. He actually says it twice.

[turbodog]

Not derailment, simply correcting your misinformation.

 

"If other factors are the same". But they aren't. ESPECIALLY when changes are made from one vehicle or mod to the next. You said it yourself. "Not accounting for VE...". VE changes dynamically, and non-linearly with MAF voltage.

 

If MAF voltage was the primary measured parameter in indicating how much power a motor can make, then people would simply plot MAF voltage vs. RPM and not waste money putting the car on some silly dyno. But they don't, because it would be worthless. ESPECIALLY when modifications come into play.

 

You DO understand that the MAF sensor simply reports a voltage, right? The flow-table is built from calibrated data. The BEST you can do, is look up mass air flow past the sensor. That is NOT the same as the mass air flow in the engine.

 

Neither of the links you posted are relevant. They simply talk about the relationship between MAF through the sensor tube and sensor voltage. That was never in question.

 

I DO like you you say that 10hp for every lb/min is "generally accepted," when the first link has one person saying that it's a VERY ROUGH guide. He actually says it twice.

 

Seriously, you may be a smart guy, but you really need to work on your reading comprehension and communication skills. You needlessly digress and dilute points inorder to.....basicly sound superior, and attempt to be right somehow. I am not impressed.

 

Where did I reference MAF voltage? I didn't. Your are straw manning me AGAIN. OBVIOUSLY the sensor outputs a voltage which is converted to a flow rate with a cal table. I am talking about mass air flow.

 

Let me go off and define something for you:

 

http://dictionary.reference.com/browse/primary

pri·ma·ry

 

adjective,

 

1. first or highest in rank or importance; chief; principal

 

Got it?

 

MAF readings (and RPM) are used to calculate the g/rev "load" which is the x axis of both the timing and fueling tables in the ECU. Gee, that MAF reading sounds pretty important to me.....hum.

 

Again allow me to restate that 1 lb/min = 10 hp is the generally accepted as approximately linear, ROUGH correlation. I don't think anyone here is claiming it is an exact correlation, except you in your straw man arguement.

 

If course the links I posted are both completely relevant as a discussion of air flow vs. HP, which should be clear to anyone who reads them with an open mind.

 

And again, obviously many other factors are in play here, but MAF is the primary factor.

[turbodog]

For anyone who doesn't know what a straw man arguement is:

 

http://en.wikipedia.org/wiki/Straw_man

 

A straw man is a type of argument and is an informal fallacy based on misrepresentation of an opponent's position.[1] To "attack a straw man" is to create the illusion of having refuted a proposition by replacing it with a superficially similar yet unequivalent proposition (the "straw man"), and refuting it, without ever having actually refuted the original position.[1][2]

 

BAC5.2 loves to use these. I have no idea why.

[thefultonhow]

I don't see how BAC is straw-manning you at all. You said that your rough guideline doesn't account for VE. He said that if you don't account for VE, the guideline is useless. Just because he said "mass air flow voltage" rather than "mass air flow" does not change that point.

 

Did he maybe misinterpret exactly what you said? Sure. But that doesn't change the ultimate point.

[MasAyinde]

So this is my rifle, It took me about 2.5 months to source all of the parts and assemble it, but I love the way it looks and shoots. It's a bit loud, but there's hardly any recoil.

 

http://i.imgur.com/wq6td.jpg

[BAC5.2]

The bottom line is that the roughness of the MAF->Power relationship is sufficient to be a completely unreliable method of comparing power output of two vehicles or one pre/post modification. No one posts MAF voltage vs. RPM in "proven power." You can argue this all you want, but you'll still be wrong.

 

I'm not going to continue arguing with you, Turbodog. You are wrong, and this discussion is over. You can continue quoting Wikipedia, looking at dictionary definitions, and whatever else you want to do to detract further from the point at hand. I'll not be privy to your little tantrums any longer.

[BAC5.2]

So this is my rifle, It took me about 2.5 months to source all of the parts and assemble it, but I love the way it looks and shoots. It's a bit loud, but there's hardly any recoil.

 

http://i.imgur.com/wq6td.jpg

 

Holy Crap! Spec/build list?

 

I'd love to build an AR for range duty.

 

I'd probably just end up spending an enormous amount of time and money designing a high efficiency suppressor too see how quiet I could get one.

 

Have you considered that route, Mas? I know the ATF license process for a suppressor is pretty expensive and tedious, but it certainly seems like it would be a neat project!